1. Field of the Invention
The present invention relates to an instantaneous water heater, more particularly one, which includes a heating tube containing heat media, a heating device over a lower end of the heating tube, a spiral pipe in the heating tube, water inlet and outlet pipes connected to two ends of the spiral pipe, and a water-discharge switch, and which will be activated to heat water immediately after the water-discharge switch is turned on.
2. Brief Description of the Prior Art
Common water heaters, which can be drinking water heaters or bathing water heaters, include a shell, a water tank held in the shell, and a heating device positioned around the water tank. In use, the water tank is substantially filled with water, and the heating device heats water in the water tank up to an intended temperature so that hot water is ready for future use; the heating device will be turned off automatically as soon as the water is heated to the intended temperature. And, the heating device will be reactivated if the water temperature becomes lower than the intended value owing to discharging of hot water and subsequent refilling the tank with cool water/heat escaping away from the hot water over time.
The above water heater has the following drawbacks:
1. The water heater will have to function to turn a full tank of water hot even if the user only needs a small cup of hot water. Therefore, it could waste electricity to use such a water heater.
2. The heating device will be reactivated every time when the temperature of water in the tank becomes lower than the intended value owing to discharging of hot water and subsequent refilling the tank with cool water/heat escaping away from the hot water over time. Therefore, it could waste electricity to use such a water heater.
3. There will be risk of the water tank burning and exploding if the protective device has a fault, and can't function properly to cut off the power to the heating device in lack of water.